This paper reports the results of a known groups validation study of several measures of teacher stress. Role-related stress, task-based stress, and environmental stress comprised the stress measures. Groups of teachers in high schools and junior high schools were selected on an a priori basis using administrative records of reported student discipline as the criterion. These teacher groups were then given a pencil and paper measure containing the three major stress variables and additional stress-related variables. Four research questions were addressed: the internal consistency of the teacher stress measures, the structural reliability of the measures, the predictive validity of the measures, and the construct validity of the measures of teacher stress. Other heuristic findings regarding the teacher stress phenomenon are discussed and substantive directions for future research are outlined. (Author)